This invention relates to a shoe provided with a closing device, especially a sport, leisure or rehabilitation shoe, with an upper material that is flexible to tensile stresses in the closing area, or with several flexible upper materials, such as natural or artificial leather, fiber, and fabric, as well as with or without trimmings, and which has an instep shield covering an instep area that can be fastened to side parts of the upper at both sides of the shoe.
A sport shoe, namely a soccer shoe, with a closure of this type is known from GDR Patent 89 796. In this previously known soccer shoe, each side of the instep shield can be fastened by a lace to a tab that is provided at each side of the shoe on side parts of the shoe upper. The lace is threaded through eyelets in the instep shield and in the side tabs, and is tied behind the heel part of the soccer shoe. With such a lacing arrangement, the point pressures which occur in tightening a lace of the usual type that runs over the instep are reduced. Thus, the circulation of blood in the instep area is no longer so greatly impaired.
However, with such a closure, in tightening or fastening the lace on both sides of the instep shield, a uniform lacing, from the lowest to the highest eyelet, is not possible. This is caused by the fact that the tensile stress from the free end of the lace to the last eyelet quickly decreases due to the high friction forces which are produced. In particular, a high friction locking between the instep shield and the side tabs, on the one hand, and the lace, on the other hand, is produced on the respective support, and the laces are squeezed in between by the closing pressure of the instep shield and side tabs as they are tightened.
The use of central tightening locks as locking devices are known for ski boots, which have plastic shell-shaped closing flaps that are, essentially, inflexible under tensile stresses; see, for example, German Auslegeschrift 20 46 890 and U.S. Pat. No. 3,738,027 which is based thereon. However, this type of closure device for inflexible alpine ski boots extends on only a short section of the closing flaps of the boot, and cannot be used on a shoe having an upper that is formed of materials that are flexible under tensile stresses (i.e., they tend to stretch) in the closing area.
A corresponding situation also applies relative to the previously known, central lock for alpine ski boots according to German Auslegeschrift 22 13 720 and the noted U.S. Pat. No. 3,808,644, in which rope loops are used as a tensioning element. Another central lock with rope loops for alpine ski boots is known from German Auslegeschrift 36 26 837. The previously known central locks cannot be produced as a prefabricated, pretested and premounted unit, so that the central locks of these alpine ski boots must be adjusted and matched to one another in each case.